I've had two operations to remove discs in my spine and two more to take out some bone pressing on the nerves. I still have back pain and numbness down my leg. I saw on the internet they can fuse the spine with special cages inserted between the bones. Have I already had too many operations to be a candidate for this new treatment?

Each doctor or clinic will have their own criteria for patient selection. The number of prior failed back surgeries isn't as important as other factors. For example you may not be considered if there are too many degenerating levels. Some doctors limit patients to three or less abnormal levels. Others will treat patients with more than three.

Severe osteoporosis or a previous bone infection may prevent you from having this type of spinal fusion. Tumors are also a problem. Current alcohol or drug abuse will put a patient at risk for a failed surgery. Heavy tobacco users also have slower and sometimes failed healing.

The use of fusion cages isn't standard everywhere. Some doctors aren't using these at all yet. Start with finding a surgeon who does use these devices and ask for an evaluation.